Fuel injection transducer and timing system

ABSTRACT

This disclosure relates to an apparatus for detecting the time of fuel injection into an internal combustion engine and the use of such intelligence in timing the engine. A transducer is mounted in relation to the fuel injection nozzle to sense and detect a shock or sonic wave resulting from opening of the nozzle at the time of injection.

United States Patent 1 Weaver May8,1973

[54] FUEL INJECTION TRANSDUCER AND TIMING SYSTEM [75] Inventor: Preston R. Weaver, Rocky Hill,

Conn.

[73] Assignee: UMC Electronics Company, North Haven,Conn.

22 Filed: Nov. 27, 1970 21 Appl. No.: 93,199

[52] U.S. Cl. ..73/1l9 A [51] Int. Cl. ..G01m 15/00 [58] Field of Search ..73/119 A [56] References Cited UNITED STATES PATENTS 3,289,077 11/1966 Miller ..73/119 A 3,344,663 10/1967 Dreisin et al. .Q ..73/l 19 A 2,192,863 3/1940 Hetzel ..73/1l9 A r 2,272,984 2/1942 Ritzmann ..73/7 1 .2 X

Primary Examiner-Jerry W. My'racle Att0mey-Delio & Montgomery [57] ABSTRACT This disclosure relates to an apparatus for detecting the time of fuel injection into an internal combustion engine and the use of such intelligence in timing the engine. A transducer is mounted in relation to the fuel injection nozzle to sense and detect a shock or sonic wave resulting from opening of the nozzle at the time of injection.

15 Claims, 7 Drawing Figures PATENTEDHAY 81975 SHEETIUFZ INVENTOR Fres+on R WCQVdF BY D4 5% M 444% v I ATTORNEY PATENTEU W 81975 SHEET 2 0F 2 xmucrm m mwSm TSMi r ZEEQEQQ MIN i w Y INVENTOR Pr s-hon R. Weaver KNEE A ORNEYLS BY DMZ WWW FUEL INJECTION TRANSDUCER AND TIMING SYSTEM This invention relates to internal combustion engines of the fuel injection type and more particularly relates to detection of the time of fuel injection in such engine and the use of such intelligence in accurately timing the engine.

Detection of the time of fuel injection in an internal combustion engine has heretofore been proposed to be accomplished by using a Hall Effect device to sense the opening of a valve in the injection nozzle. This requires a specially built injection nozzle with Hall Effect elements integrally built in to sense opening of a valve. Such arrangements could lead to a rather expensive injection nozzle valve, particularly since the nozzle valves are replaceable items and are generally completely replaced and not repaired as a maintenance item. An effective way of determining the time of fuel injection, as disclosed in .U. S. Pat. No. 3,51 1,088 and copending application Ser. No. 60,429 filed Aug. 3, 1970 and now [1.8. Pat. No. 3,698,249 is detection of a signal responsive to expansion of the injection line and conditioning a signal responsive thereto. The enumerated patents disclose the use of a transducer coupled to the injection line which generates a signal which varies as a function of the pressure in the line. Such systems have given excellent performance by providing a signal which varies as a function of the fuel charge and which allows the time of the charge reaching a predetermined pressure to be determined with great precision.

The present invention provides an improvement over these aforementioned techniques of determining the time of fuel injection by providing a transducer which is coupled to the fuel injection nozzle holder and is a permanent portion of the engine, remaining there even though the injection valve may be periodically changed.

Briefly stated, the invention in one form thereof comprises a transducer in the form of an accelerometer or contact microphone which is so mounted as to detect relatively high frequency mechanical or sonic impulses which exist on the injector or any other related rigid structure when fuel is injected into the cylinder. The detected signal which appears in the form of a relatively high frequency mechanical or sonic wave is converted to an electrical signal which may be utilized for engine timing, to indicate engine speed, or other purposes.

An object of this invention is to provide a new and improved technique of detecting the time of fuel injection in an engine of the internal combustion type.

Another object of this invention is to provide a transducer which may be easily mounted to a rigid portion of an engine to detect the time of fuel injection into a cylinder.

A further object of this invention is to provide a new and improved system for timing an internal combustion engine of the fuel injection type through detection of the mechanical or sonic impulse which exists when fuel is injected into a cylinder.

The features of the invention which are believed to be novel are distinctly claimed and particularly pointed out in the concluding portion of this specification. However, the invention both as to its organization and operation, together with further objects and advantages thereof, may best be appreciated by reference to the following detailed description taken in conjunction with the drawings, in which:

FIG. 1 is a diagrammatic arrangement partly in section of the fuel injection pump and injection nozzle and cylinder of an internal combustion engine;

FIG. 2 is a view in half section showing a transducer mounted in proximity to the injection nozzle in accordance with the invention;

FIG. 3 is a view in section showing an alternate technique of mounting a transducer to sense opening of the nozzle; I

FIG. 4 is a waveform diagram of an electrical waveform resulting from the detected valve opening;

FIG. 5 is a view in longitudinal half section of a typical nozzle valve;

FIG. 6 is a diagram in schematic block form showing a network for conditioning the detected signal to a more useful form; and

FIG. 7 is a side view partially cut away of another transducer which may be utilized in the practice of the invention.

As shown in FIG. 1, fuel is injected in the cylinder 10 of an internal combustion engine, which as shown is of the diesel type when the piston 11 is at or near the top dead center (TDC) position. Such fuel injection occurs at injection nozzle 12 carried in a housing 13 which is mounted to the engine block. A fuel pump 14 supplies fuel through a line 15 to the nozzle 12. The injection nozzle 12 consists of the body portion 16, a holding nut 17 and a nozzle valve assembly 18, as more clearly shown in FIG. 5. Nozzle assembly 18 includes a valve 19 which is normally seated as shown against a valve seat member 20. The end 21 of valve stem 22 is acted upon by a spring 23 which biases the valve stem and, therefore, the valve into a closed position by acting against aspring seat 24 at end 21 of the valve stem. The other end of spring 23 acts against insert 25. When pressure acting on the valve through aperture 26 reaches a sufficient value, the valve is opened and fuel is injected into cylinder 10 through a pre-combustion chamber 28 defined by housing 13 and mounting member 29. The design of the nozzle shown is such that the valve member does not bottom on portion 27.

The particular fuel pump valve assembly and injection nozzle is the type marketed by Caterpillar Tractor Company. This particular arrangement is shown for purposes of orientation. It is to be understood that the invention may be applicable to any type of nozzle or nozzle valve.

In accordance with the invention, a shock or ultrasonic wave which is produced by the opening of the injection nozzle valve is detected, .and then conditioned to provide a useful signal. It has been determined that the opening and closing of the nozzles produce a wave or pulse which travels through the nozzle and its related parts, some of which are easily accessible. When the pressure built up by the fuel injection pump reaches a predetermined value, usually 1,000 to 3,000 pounds per square inch, the spring 23 in the nozzle valve will be compressed and fuel will suddenly flow out of the nozzle into the pre-combustion or combustion chamber. The sudden flow of the fuel causes a shock or sonic wave to be imparted to the nozzle and through the nozzle to the adjoining parts. The transducer is placed at the most convenient spot, which as shown is on the housing for the injection nozzle and valve assembly, which is in turn mounted to the head of the engine.

The transducer shown in FlG. 2 is mounted to the housing 13 and generally comprises a piezoelectric transducer 33 in disc form. The piezoelectric disc 33 is sandwiched between masses 34 and 35. A conductive layer 36 is provided on one surface which is in contact with an insulating disc 37. This assembly is disposed within an enclosure shown as two-part can 38 which is mounted to housing 13 as by means of a central bolt 39 which is threadably received in a socket 40 suitably drilled and tapped in housing 13. An insulating sleeve 41 is provided about bolt 39. Spacing washers 43 and 44 are provided beneath the head of the bolt and the bottom of the can, respectively, to rigidly mount the transducing arrangement 32 to housing 13.

The transducer may also be bonded to the housing as shown in FIG. 3. A transducer 45 comprises a cupshaped housing member 46. Disposed at the bottom of the heading is a mass 47 and resting thereon is a piezoelectric disc 48 having a conductive coating 49 thereon. The lower side of the disc 48 is in ground contact with mass 47 and the upper surface with the coating 49 thereon is insulated from an upper mass 47a by an insulating washer 50. A sleeve-like member 51 disposed about disc 48 provides insulation with respect to the housing 46. A closure member 52 is threadably received in the upper portion of housing 46 and is screwed down to provide the desired preloading on disc 48. A signal lead 53 is taken from the conductive coating 49 and the ground lead 54 may be taken from the lower mass 47. The housing member 46 is adhesive bonded to the injector housing 13. A suitable adhesive to rigidly bond the transducer to housing 13 is Eastman Kodak 910 adhesive.

In operation, when the valve in nozzle 18 opens, a shock or sonic wave is transmitted throughout the entire nozzle assembly which will impart acceleration to one of the upper and lower masses of the transducer tending to compress the piezoelectric element therebetween.

The pump 14, through a cam 14a acting on follower 14b and piston 14c creates pressure on fuel brought into cylinder 14d from fuel line l4e. As cam 14a approaches top position an increasing pressure is exerted on the fuel in line and in the nozzle valve. When the pressure of the fuel in the nozzle valve reaches a predetermined value the valve seat unseats, and fuel is expelled from the valve into the pre-combustion chamber. This sudden release of energy produces an acoustic and shock wave to be imparted to the nozzle' and adjoining parts.

Associated with this shock wave is an ultrasonic wave due to the complex motion of the fluid as it is suddenly released and interacts with boundaries in relative motion or as it experiences turbulent motion. Altematively, the mechanical shock may be produced by the ultrasonic wave. This phenomena is analogous to striking a metallic rod with an object. In either case, a piezoelectric transducer or crystal pickup will detect the shock produced in the rigid structure of the injector assembly. Additionally, the acoustic noise produced by the opening and closing of the nozzle valve may be detected.

The connection of the transducer to the injector assembly should be solid so that no relative motion exists therebetween.

The resulting output from the transducers is shown in waveform A of FIG. 4 in timed relation to the pressuretime signal B detected on line 15 through use of an online transducer as shown in U. S. Pat. No. 3,51 1,088.

This comparison clearly shows that a sonic or mechanical shock wave is generated or created at the time of opening of the nozzle which corresponds to the pressure buildup in the injection line 15 at the time of fuel injection. This impulse is transmitted through the rigid nozzle structure and is detected by a transducer as shown in FIG. 2 or 3. A mechanical stress is created on the piezoelectric element which is converted to an electrical impulse as shown in FIG. 4(A).

FIG. 6 exemplifies a signal conditioning circuit which may be utilized in conjunction with the invention. The output of the transducer exemplified as transistor 32 is applied by coaxial cable and connector 60 to an amplifier 61 in the form of an FET source follower by a voltage divider 62. The output of the source follower 61 is applied to a band pass filter 63 and, hence, to a detector 64 and amplifier 65. The band pass filter 63 is selected to pass a signal in a given frequency range which will be the signal due to the impulse resulting from opening of the valve.The particular band pass may depend upon the particular nozzle valve as well as the characteristics of the transducer, as will hereinafter be discussed. Detector 64 detects the envelope of the high frequency wave and provides a pulse or series of pulses to amplifier 65. The band pass filter further isolates signals due to other vibrations set up by operation of the engine. An output signal may be observed by means of a scope or other waveform measuring device connected to terminal 65a.

If desired, an oscilloscope 65b may be utilized to observe the waveform before detection. The pattern of the waveform may be analyzed to determine the operational condition of the nozzle valve, as to leakage, wear, etc.

The output of amplifier 65 is also applied to a voltage level sensor 66 which will provide an output signal in response to an input signal of a reference threshold value as may be determined by the setting of a potentiometer 67. The output of the voltage level sensor is then applied to a pulse generator 68 which may be a one-shot multivibrator (OSM). The period of the OSM is selected to be sufficiently long that any second and succeeding pulses from amplifier 65 have no effect thereon. The output of pulse generator 68 is applied to a strobe or timing light 69 directed to the piston TDC and angle or timing markings on the flywheel 70 and adjacent block of engine 71. The output of pulse generator 68 may also be applied to a tachometer 72 to provide an indication of engine speed.

In one application of the invention it may be utilized to measure the angle between the time of fuel injection and the TDC position of a piston in the cylinder. In this case, the angular position between the time of firing and the time of TDC position of the cylinder may be observed from the usual scale mounted on the engine block in relation to the marking on the flywheel.

Alternatively, instrumentation may be provided in which the TDC position is indicated by a signal from a magnetic sensor 74 which is mounted to the flywheel and engine. The signal from magnetic sensor 74 is applied to a pulse shaper 75 such as a one-shot multivibrator. The output of pulse generator 68 at time t and the output of pulse shaper 75 at time 2 are applied to a comparison network 76 which may be in the form of a bistable multivibrator. The successive signals will cause the states of conduction of the multivibrator 76 to shift during the pulses t and t which will indicate the difference in time or angular position. In this case, the time 2 and t taken together with the time between successive t s is the measure of the angular displacement or time between fuel injection and the TDC position of the particular cylinder.

It has been determined through search with a band pass filter that the mechanical shock or ultrasonic wave is exerted on the mechanical structure due to the release of the fuel under pressure to the nozzle valve.

A search with a band pass filter on the particular valve tested showed that at a center point of 20-30 KHz there was a definite signal produced which is believed to be due to the shock created by the release of fluid when the valve opens. In another test using a crystal contact microphone rigidly coupled to the injector housing an audible signal in the frequency range of 2000-3000 Hz was detected. This was the noise of valve opening and closing.

When the transducer is in the form of a crystal microphone it may take the form shown in FIG. 7. A crystal 80 having conductive layers 81 and 82 on either side thereof is mounted to a plate 83 which may be of brass and grounded thereto by means of conductive layer 82. A suitable insulation 84 which may be molded to shape is disposed over the crystal and bonded or otherwise secured to plate 83. This assembly may then be contained in a cover member 85 and electrical leads suitably taken from plate 83 and layer 81 to a coaxial cable connector 86. This contact microphone type device may be rigidly mounted to the injector housing as by means of an adhesive to detect the noise due to opening and closing of the valve. This noise which will be in the range of 2000-3000 Hz is detected through the network of FIG. 6, the only difference being in the range of the band pass filter.

It may be necessary to initially search the output of the transducer through a band pass filter to detect the particular frequency of the signal imparted to the transducer, dependent on the parameters of the injection nozzle, fuel pressure, etc., of a particular type engine to determine the frequency of the impulse.

The transducer is arranged generally in the form of an accelerometer or contact microphone so that the mechanical forces exerted on the piezoelectric element are due to the acceleration imparted to either of the masses.

The transducer may be relatively small as exemplified in FIG. 1 and permanently mounted to a point on the engine which will be subjected to the shock or sonic wave created by release of fuel by the injector.

From the foregoing disclosure it may seen that the objects of the invention are efficiently attained. While preferred embodiments of the invention have been set forth for purposes of disclosure, it is to be understood that other embodiments to the invention as well as modifications to the disclosed embodiment which do not depart from the spirit and scope of the invention may become apparent to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments and modifications of the invention which do not depart from the spirit and scope of the invention.

What is claimed is:

1. For use in combination with an internal combustion engine of the fuel injection type having injection nozzles within nozzle housings adapted to inject fuel under pressure into the cylinders of the engine, transducer means mounted to a nozzle housing for sensing impulses created by fuel flow upon opening of the nozzle and generating an electrical signal in response thereto, filter means responsive to said transducer for detecting the signal corresponding only to a shock wave created by release of fuel under pressure by the nozzle, and means for detecting the electrical signals passed by said filter means.

2. The apparatus of claim 1 further including means for converting the detected electrical signal to a pulselike signal and detecting a predetermined amplitude thereof.

3. The apparatus of claim 2 further including means for measuring the time between detection of the predetermined amplitudes.

4. The apparatus of claim 2 further including a lamp, the pulse signal being applied to said lamp to produce illumination thereof.

5. The apparatus of claim 1 further including means for indicating a predetermined position of a piston in the cylinder, and means for measuring the time between the sensed detected signal and the time of said piston reaching said predetermined position.

6. The apparatus of claim 1 wherein said transducer is a piezoelectric element, a housing for supporting said element, said housing being rigidly mounted to said injection nozzle.

7. The apparatus of claim 1 wherein said transducer comprises a wafer of piezoelectric material between two masses, a housing member enclosing said masses and said material, and means rigidly mounting said housing to a nozzle housing.

8. The apparatus of claim 1 further including means responsive to the detected electrical signal for indicating the speed of the engine.

9. A method of determining the time of fuel injection into a cylinder of an internal combustion engine wherein a nozzle releases fuel under pressure into a cylinder comprising the steps of determining the time of opening of the nozzle by sensing impulses created by fuel flow upon opening of the nozzle, and converting said impulse to an electrical signal corresponding only to a shock wave created by release of fuel under pressure.

10. The method of claim 9 including the further step the time between the electrical signal and the time the piston is in the predetermined position.

13. Apparatus for use in analyzing the condition of fuel injection nozzles of an internal combustion engine within a nozzle housing, comprising a transducer mounted to the nozzle housing for sensing the shock wave created upon release of fuel under pressure by the nozzle and producing an electrical signal responsive thereto, filter means coupled to said transducer for passing an electrical signal corresponding to the shock wave created by fuel flow through the nozzle, and visual display means coupled to said filter means to dis- 

1. For use in combination with an internal combustion engine of the fuel injection type having injection nozzles within nozzle housings adapted to inject fuel under pressure into the cylinders of the engine, transducer means mounted to a nozzle housing for sensing impulses created by fuel flow upon opening of the nozzle and generating an electrical signal in response thereto, filter means responsive to said transducer for detecting the signal corresponding only to a shock wave created by release of fuel under pressure by the nozzle, and means for detecting the electrical signals passed by said filter means.
 2. The apparatus of claim 1 further including means for converting the detected electrical signal to a pulse-like signal and detecting a predetermined amplitude thereof.
 3. The apparatus of claim 2 further including means for measuring the time between detection of the predetermined amplitudes.
 4. The apparatus of claim 2 further including a lamp, the pulse signal being applied to said lamp to produce illumination thereof.
 5. The apparatus of claim 1 further including means for indicating a predetermined position of a piston in the cylinder, and means for measuring the time between the sensed detected signal and the time of said piston reaching said predetermined position.
 6. The apparatus of claim 1 wherein said transducer is a piezoelectric element, a housing for supporting said element, said housing being rigidly mounted to said injection nozzle.
 7. The apparatus of claim 1 wherein said transducer comprises a wafer of piezoelectric material between two masses, a housing member enclosing said masses and said material, and means rigidly mounting said housing to a nozzle housing.
 8. The apparatus of claim 1 further including means responsive to the detected electrical signal for indicating the speed of the engine.
 9. A method of determining the time of fuel injection into a cylinder of an internal combustion engine wherein a nozzle releases fuel under pressure into a cylinder comprising the steps of determining the time of opening of the nozzle by sensing impulses created by fuel flow upon opening of the nozzle, and converting said impulse to an electrical signal corresponding only to a shock wave created by release of fuel under pressure.
 10. The method of claim 9 including the further step of generating an electrical pulse when said electrical signal reaches a predetermined value.
 11. A method as specified in claim 9 including the further step of utilizing said electrical signal to operate a timing light and utilizing said light to view timing markings on the flywheel of the engine.
 12. A method as specified in claim 9 further including the steps of determining when the piston in the cylinder is in a predetermined position, and measuring the time between the electrical signal and the time the piston is in the predetermined position.
 13. Apparatus for use in analyzing the condition of fuel injection nozzles of an internal combustion engine within a nozzle housing, comprising a transducer mounted to the nozzle housing for sensing the shock wave created upon release of fuel under pressure by the nozzle and producing an electrical signal responsive thereto, filter means coupled to said transducer for passing an electrical signal corresponding to the shock wave created by fuel flow through the nozzle, and visual display means coupled to said filter means to display the electrical signal.
 14. Apparatus of claim 13 further including means for detecting the envelope of the electrical signal.
 15. A method of analyzing the condition of a fuel injection nozzle which passes charges of fuel under pressure comprising the steps of sensing the shock wave created by release of fuel under pressure through the nozzle converting the shock wave to an electrical signal, and displaying the waveform of the signal for visual inspection. 